Temperatures close to absolute zero are required for the operation of quantum computers. Cooling to such values often proves to be difficult. But not so for a research team at the TU Munich.

Basic research in quantum physics uses low temperatures. In addition, there are more and more developments based on quantum mechanical effects such as quantum computers. However, very low temperatures – near absolute zero of -273 °C – are needed to operate these applications. This requires sophisticated cooling systems, which are particularly in demand at the moment.

For this reason, a team of researchers at the Technical University of Munich has dedicated itself to cooling technology and founded the start-up »Kiutra«. Alexander Regnat, Jan Spallek, Tomek Schulz and Prof. Christian Pfleiderer are currently working on a prototype of a magnetic cooling system for quantum electronics. Further employees and the company's own headquarters are already in prospective.

Magnetic cooling vs. gas cooling

Liquid gases are often used to achieve cooling to very low temperatures. In order to maintain such a temperature permanently, the very expensive isotope helium-3 is usually used.

An alternative are magnetic cooling processes, which generate the low temperatures with favourable solids. However, they can only maintain the temperature for a short period of time. The principle of magnetic cooling is based on the magnetocaloric effect. In the single-shot Adiabatic Demagnetization Refrigeration (ADR) method, a cooling medium is magnetized and the heat generated is dissipated. During the subsequent demagnetization, cold is produced which cools the medium constantly for a certain period of time.

CADR method leads to success

However, the technical implementation of permanent magnetic cooling has so far been very demanding. The research team at TU Munich has now further developed the ADR method. In the Continuous Adiabatic Demagnetization Refrigeration (CADR) method, several cooling units are interconnected. This ensures that there are always enough cooling units available, while the heated units can regenerate. In this way the absolute zero point is permanently reached and sustained. And that only with electricity, without expensive Helium-3.

Kiutra already sells the magnetic coolers with the ADR method in three variations with different specifications. The team is currently working on the marketability of the CADR cooler. Kiutra is supported by an Exist-founder-scholarship and received a validation grant from the Free State of Bavaria.